The present invention relates generally to the field of Internet software applications; more particularly, to web systems that provide the capability to upload digital information to a web page.
A web camera (i.e., xe2x80x9cwebcamxe2x80x9d) system consists of a video camera plus software that runs on a personal computer to periodically upload an image from the camera to a web page. The basic purpose of a web camera system is to post a reasonably live picture on a user-specified web page. Many webcam systems upload images on a periodic basis; for example, uploading an image once per hour. People use the cameras to show live pictures of, among other things, offices, homes, and backyards.
FIG. 1 illustrates a typical web camera system 10 that includes a video camera 11, personal computer (PC) 12, and a web server 13. Video camera 11. outputs a captured video image to PC 12. Software running on PC 12 operates to periodically upload the captured video image to an Internet web page (i.e., web server 13). Internet service providers (ISPs) commonly provide their patrons with a certain allocation of web page space for personal use. This allows the user to upload images onto their web page periodically; with the frequency of uploading being dependent on the particular type of connection offered by the ISP.
Presently, there are two shareware products in existence that relate to web cameras: Ispy(trademark) and Webcam32(trademark). The Ispy webcam software functions to grab video images, save them as JPEG files, and then send the saved images automatically to a user-specified home page via the connection provided by the users"" ISP. Ispy runs under WindoWs(trademark) 95, Windows 98 and Windows NT 4.0; it also works with any video for Windows-compatible cameras and frame grabbers. Webcam32 is a Windows 95, Windows 98 and Windows NT application that allows video camera images to be displayed within a Web page. Like Ispy, Webcam32 software is able to upload images to a web server to allow images to be obtained directly from the page.
Both of these products include various simple image-processing features such as captioning of photos, day/time stamping, and text additions. Both products give the user choice either running according to a preset schedule, or uploading images based on rudimentary motion detection. For example, it is possible to establish a schedule wherein no uploads occur before 8 a.m. or after 8 p.m. This type of schedule is suitable for, say, an office environment, where there is regular activity occurring during the predetermined schedule times.
The trouble with both of these products is that there are certain instances where uploading according to a predetermined schedule does not work well. One case is an office environment where regular work hours are not kept. Another problem arises when the times of sunrise and sunset change with the changing of the seasons. This latter problem is more pronounced at locations having a high latitude.
Some web camera systems capture a live image 24-hours a day, uploading a totally dark picture when the office lights are turned off, or when the sun has set. In some cases, these systems upload a solid blue or green image whenever the camera is turned off. Avoiding image capture during certain times, however, doesn""t solve the aforementioned problems because the time of sunrise and sunset can vary dramatically during the year. In addition, the camera owner might turn off the camera at any time during the day.
Therefore, what is needed is a web camera system that is capable of detecting a dark image, or when the user is turned the camera off, assuring that. only interesting pictures appear on the user""s web page.
The present invention, in one embodiment, comprises a method of operation for a web camera system. The method includes generating an intensity histogram from an image captured by a video camera. The intensity histogram provides a distribution of pixel intensities across a range from a minimum to a maximum intensity. The image is marked as having low contrast when a width of the distribution is less than a predetermined threshold value.